Furniture conservator Mark Anderson examines a table in the collection.

Furniture Conservation

The Furniture Conservation Lab is responsible for the care and treatment of approximately 9,000 pieces of furniture and wooden objects in the collection. The conservators are concerned with both structural and surface issues. They maintain and stabilize the structure of objects that may have been damaged or poorly repaired in the past, suffered an insect infestation, or were weakened by exposure to water damage or a poor environment. Historic surfaces, both transparent and painted, change and deteriorate over time resulting in crackling, flaking, uneven darkening, fading, blanching, scratches, and stains. Conservators balance preserving early surfaces and the history they embody with maintaining an aesthetic appearance that respects the intent of the original maker.

Working with textile conservators, furniture conservators also care for upholstered furniture. They preserve and stabilize existing upholstery structures and show fabrics when they are historically appropriate and in stable condition. When the upholstery is inappropriate and/or the structure or show fabric is too deteriorated, the upholstrey is replaced with a non-invasive structure that avoids nailing or tacking into the original wood.

Preventive Conservation

To lessen the risk of damage to its furniture collection, Winterthur maintains a stable environment with an average temperature of 68–70° F and a relative humidity of 45-55%. A stable relative humidity is particularly important to furniture since rapid changes cause different parts of the object to expand and contract at different rates and to different degrees. A poorly controlled environment can cause detached veneer, cracks, and flaking paint. Since insects like the powder post beetle can cause serious damage to wooden objects, preventive conservation aides carefully monitor for evidence of insect activity. Excess light can cause surfaces and upholstery fabrics to fade or darken so exterior windows are modified to reduce ultraviolet and visible light. The Wintethur lighting specialists design interior lighting to minimize damage while giving visual access to our guests.

Clock before treatment

Clock base before treatment with old repair removed.

A Study in Challenges - the Peter Stretch Clock

The most ornate eighteenth century Philadelphia tall case clock (2004.51) in Winterthur's collections was made by an anonymous cabinetmaker to house the works made by the Philadelphia clockmaker Peter Stretch (1670–1746). Like many tall case clocks, it has suffered losses including its original base molding (or feet) as well as 64 dentils ornaments along the moldings of the bonnet. The finish of the clock was also uneven, dark and degraded with numerous losses, particularly in areas of previous repairs.

(Left) Furniture conservator Stephanie Auffret replaces a missing dentil. (Center) Detached elements of the fretwork are being studied and secured back in place. (Right) Plaster cast of molding that will be used for the new base.

In consultation with the furniture curator, conservators decided to replace the missing dentils and created a design for the missing base after studying other similar clocks. Because the new base is not original to the clock, it is designed for easy removal. The most difficult decisions were whether and how to clean or alter the finish to reveal the highly figured mahogany of the case and create a unified appearance for the clock. Extensive analysis by the Scientific Research and Analysis Laboratory (SRAL) revealed the structure and composition of the finish layers. Although the dark and crackled finish obscures the highly figure mahogany of the case, curators and conservators decided, after much consultation, that it should be preserved. To create a unified appearance, the finish was cleaned in a manner that left the finish intact. Molds taken of deteriorated finish areas were used to create finish coating fills for the losses that matched the texture and color of the original.